Friday, July 4, 2014

Polar plots NSIDC Sea Ice data


For some years now I have maintained a page of automatically updated data about surface (and LT) temperature and JAXA Arctic Sea Ice Extent. NSIDC now keeps a regular schedule with their Arctic and Antarctic Sea Ice Extent updates, so I'd like to include them.

The sources are: JAXAand NSIDC
. Note that the NSIDC files come in two parts, final (to late 2013) and nrt (from then to date).

I am simply extending the existing presentation which consists of a window of numerical data, and an active polar plot. Both now have radio buttons so you can choose from among the three datasets. The window also has an enlarge option. The table has recent data at the top, but if you scroll down, there is more.

As soon as it is working smoothly, I'll add this all to the regular page.

Here is the table. The enlarge button is a toggle.


JAXA Arctic
NSIDC NH NSIDC SHEnlarge



And here is the active polar plot of sea ice extent data. The radio buttons at the top change the dataset, with maybe a second or two to reload. Units are million sq km. You can click on the current region circle to get a magnification, or on any sector to see that part expanded. Clicking on the legend marks the year in dark; clicking on the central picture makes it go away. Details here.



I'm experimenting with adding dots to make the curves more distinct. The legend indicates both line and dot colour. I'm still trying to decide if it's a nett benefit.

NSIDC has data going back a lot further. I've currently stuck to the range as in JAXA, else the plot gets very cluttered.



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